عنوان مقاله English
نویسندگان English
The study area is located in the north of Narmashir County, in the southern part of the Lut Block structural-sedimentary zone and north of the Jazmurian subsidence. This region is important from a tectonic perspective because it is located at the collision point of two tectonic plates and has witnessed extensive volcanic activity. Based on petrographic studies, the volcanic rocks of the region include a wide range of compositions of basalt, olivine basalt, andesite, basaltic andesite, trachyandesite, dacite, rhyodacite, and rhyolite. Geochemical studies show that the rocks of the region are tholeiitic to subalkaline in nature, high in potassium and meta-aluminous to weak peraluminous. Among the prominent geochemical characteristics of these rocks are; Enrichment of light rare earth elements (LREE), large ion lithophile elements (LILE) and depletion of high ionic potential elements such as tantalum (Ta), niobium (Nb) and titanium (Ti). The values of Nb / La and Nb / U ratios, as well as the Sm / Yb ratio between 6.1 and 9.2, indicate contamination of the primary magma with crustal materials. Furthermore, the increase in Ce / Yb ratio along with the increase in Ce concentration could indicate the presence of garnet mineral in the melt source. The findings of this study indicate that the volcanic rocks of northern Narmashir were formed in a tectonic environment related to subduction. The initial magma resulting from partial melting of the mantle has been contaminated with continental crust while ascending to the Earth's surface and has experienced varying degrees of magmatic differentiation. The presence of garnet in the melt source has also played a role in the evolution of the chemical composition of these magmas. The lithological diversity and geochemical characteristics of these rocks clearly demonstrate the complexity of petrogenetic processes in this tectonically active region.
کلیدواژهها English